Those in the dentistry art have attempted for many years to devise improved techniques for repair of teeth, and specifically, for the restoration of large cavities and other damage to teeth. The most conventional materials include a silver mercury compound which is packed into the cavity and allowed to harden. Excess portions are then removed so that the tooth is substantially restored to its natural shape and form.
While the silver is somewhat unsightly, it is the mercury which is more of a concern. Mercury is a poisonous material and many individuals do not like the idea of having it used in their Mouth. Accordingly, there has recently been a tendency to use other types of materials to repair teeth.
One set of such alternative materials are light curable resins. These materials have the physical property that they harden and bond to the teeth when exposed to a predetermined frequency of light. The frequency is typically that characteristic of ultraviolet. Typically, these materials are much more putty-like than the mercury silver materials which have substantially more body. These light curable materials are often applied using matrix bands to assist in the formation and shaping of the final restoration. The matrix bands provide a fixed volume to which the material is confined.
With reference to FIG. 1, shown therein is a top view of a damaged tooth 101 surrounded by two substantially undamaged teeth 102 and 103. It can be appreciated from FIG. 1 that the damage 104 in tooth 101 needs to be filled in with the silver mercury compound, the resin, or other material, in order to repair the tooth.
FIG. 2 shows the teeth of FIG. 1 with a matrix band 201 surrounding damaged tooth 101. In accordance with prior art techniques, the matrix band 201 is wrapped around tooth 101 and tightened by use of apparatus 202, commonly known as a matrix band and retainer. One commonly used type of such arrangement is known as a tofflemire retainer. The matrix band 201 is often constructed of thin metal, but may even be constructed of a thin light transparent film in case a light curable material, such as that previously discussed, is utilized to repair the damage 104.
The problem in the art is that the light permeable material is similar to a film, and is extremely thin and flimsy, much more so than the metal. The light permeable film wraps quite tightly around the damaged tooth, and thus leaves a large gap between, for example, teeth 101 and 103. This gap 207 is clearly shown in FIG. 2.
Ideally, it would be desirable for the restored tooth to be anatomically similar to the original tooth. This means that adjacent teeth should contact each other in the upper one-third portion of the interproximal area, and not contact one another along the remainder thereof. This is shown in FIG. 11.
FIG. 3 shows a similar arrangement to that of FIG. 2 except that the matrix band 301 is now constructed of a thin metallic material. Since the metal is much thicker and less malleable, the matrix band does not fully conform to the shape of tooth 101, but rather, is somewhat separated from tooth 101, at the sides thereof. As a result, the matrix band abuts, or nearly abuts, adjacent teeth 102 and 103 as shown. Indeed, the difference between FIGS. 2 and 3 can best be appreciated by viewing the interproximal spacing in both figures between teeth 102 and 101, and between teeth 103 and 101. It can be appreciated from FIG. 2 that filling in the bonding material to damaged portion 104 in FIG. 2 will result in large interproximal spacing between teeth 101 and 103. On the other hand, filling the bonding material into damaged portion 104 in FIG. 3 will result in much less interproximal spacing. However, since the matrix band of FIG. 3 is metallic, no light curable material can be used. The matrix band will not allow the light to permeate through to the curable material.
Those of ordinary skill in this art appreciate the desirability of minimizing interproximal spacing along the top portions of the teeth. For example, large interproximal spacing results in food debris being trapped between the teeth after repair. Other problems include periodontal disease, potential tooth decay, and orthodontic shifting, even resulting in a potential change of the patient's bite.
However, in view of the above discussion, it can also be appreciated that it is difficult to minimize interproximal spacing, in any part of the interproximal area, if a light curable material is used for tooth repair. This problem is due to the fact that the thin flimsy film-like material which is used to construct matrix bands for use in connection with light curable material conforms to the tooth being repaired, as shown in FIG. 2.
In view of the above, it can be appreciated that there exists need in the art for a better technique of allowing light curable materials to be utilized in the repair of damaged teeth to obtain anatomically correct restorations.